What Was Velociraptor Really Like? Turkey-Sized, Feathered and Nothing Like the Film

Velociraptor mongoliensis was described in 1924 from a skull and a claw found in the Gobi Desert by the American Museum expedition, and it belongs to the dromaeosaurs, a family of small to medium theropods with a stiffened tail, a large sickle-shaped claw held off the ground on the second toe of each foot, and, as has been known since the 1990s, feathers. It was about two metres long from nose to tail tip, half a metre high at the hip and around fifteen to twenty kilograms, with a long low skull of about 25 centimetres holding some eighty teeth, and long arms with three-fingered hands. A specimen described in 2007 has quill knobs on its forearm, the bumps where the shafts of large feathers anchored, and no doubt remains that the arms carried wings, useless for flight in an animal of that weight but inherited from smaller flying ancestors.

In 1971 a Polish-Mongolian expedition found a Velociraptor and a Protoceratops, a pig-sized horned dinosaur, buried together in the act of fighting. The raptor's sickle claw is in the throat of the Protoceratops, its right arm is in the Protoceratops's beak, which has bitten down on it, and the two seem to have been buried in an instant by a collapsing dune, in a struggle that had reached a stalemate. The fossil, kept in Ulaanbaatar and shown around the world, is the only direct record of a predatory dinosaur attacking its prey, and it answers a question about the claw: it was used to stab and hold at the neck rather than to slash the belly, as the films show, since the claw's curve is for gripping and its edge is not sharp.

The evidence, from the fighting pair, from the closest living relatives and from the biomechanics:

• •The sickle claw pinned prey, like the talon of a hawk on a rabbit, while the jaws did the killing, a method called raptor prey restraint proposed in 2011 from the way birds of prey use their feet
• •The wings and tail were for balance during the pin, flapping to keep the animal on top of struggling prey, which is what a hawk does
• •Prey was small: Protoceratops was about the raptor's own size, and a pterosaur bone found in a Velociraptor's gut in 2012 was probably scavenged
• •Pack hunting is unsupported: no bone bed of multiple Velociraptors exists, and the tooth isotopes of the related Deinonychus show the young ate differently from the adults, which coordinated packs do not do
• •It was probably nocturnal, since the ring of bones in its eye is proportioned like a night hunter's

Michael Crichton, writing the novel in 1990, followed a book by Gregory Paul that lumped the American Deinonychus, three metres long and seventy kilograms, into the genus Velociraptor, and used the shorter name; the film's designers then made the animal larger still, and its skin was scaled because the feathers of dromaeosaurs were unknown until 1996, when the first feathered dinosaurs came out of China. A raptor of twenty kilograms with wings and the intelligence of a large bird would not have made the same monster, and the film's version has been more influential than any fossil, so that the discovery in 2007 of the quill knobs was reported worldwide as the news that the raptors had feathers, which palaeontologists had assumed for a decade.

Velociraptor and its family are the dinosaurs nearest to birds, and every discovery about them, the feathers, the wings, the brooding posture of their relative Oviraptor, the hunting style shared with hawks, has closed the gap between the two. The animal is also the best case of the way popular culture and science diverge: the name is known to everyone, and what it names is known to few. The real Velociraptor was a feathered, warm-blooded, probably nocturnal predator of the Cretaceous desert that pinned prey with its foot and once died with its claw in a Protoceratops's throat, and it deserves the fame the film gave to something else.

Most of what is said confidently about Velociraptor's soft body was never preserved in its own fossils. Palaeontologists reach it by a method called phylogenetic bracketing: if a feature is present in an animal's close relatives on either side of it on the family tree, it was very probably present in the animal too. Birds sit on one side of Velociraptor, and several related dromaeosaurs and earlier feathered theropods from China, preserved in fine lake sediments with full coats of feathers, sit on the other. Feathers on Velociraptor were therefore a safe inference years before the quill knobs turned up to confirm it.

The same method marks the limits of what can be known. Colour cannot be bracketed, because it varies too much between close relatives, and can only come from direct evidence. In exceptionally preserved fossils, microscopic pigment-bearing structures called melanosomes survive, and their shapes can be matched to those that produce particular colours in living birds; this has shown that the small Chinese dromaeosaur Microraptor had glossy, iridescent black plumage like a crow's. No Velociraptor fossil from the desert sandstones of the Gobi preserves any feathers at all, so the colour of any reconstruction you see is an artist's choice.

Velociraptor sat in the middle of a family with an enormous range of sizes. At the small end was Microraptor, from China about 120 million years ago, an animal less than a metre long, much of it tail, and weighing around a kilogram. It had long flight feathers not only on its arms but on its legs too, giving it four wing-like surfaces, and it was probably able to glide or fly between trees. Its fossils, preserved in fine lake mud, show that the feathered arms of Velociraptor belonged to a family in which some members really did take to the air.

At the other end was Utahraptor, from the Early Cretaceous of Utah, discovered in 1991 and named in 1993, the year the film came out. Estimates put it at around six metres long and several hundred kilograms, bigger than the film's animals, though it tells us nothing new about Velociraptor itself. Dromaeosaurs also lived on the southern continents, where some had long, narrow snouts that hint at a diet of fish. Studies of the family tree suggest that large size evolved from smaller ancestors more than once in the group, which is why knowing one member tells you surprisingly little about the others.

Velociraptor was discovered by an expedition from the American Museum of Natural History, led by Roy Chapman Andrews, which explored Mongolia's Gobi Desert in the 1920s in search of early humans. They did not find human ancestors, but they found an extraordinary wealth of dinosaurs and some of the first dinosaur eggs recognised as such, at a site they called the Flaming Cliffs.

In 1923 a crushed skull and a large claw were found there, and in 1924 the museum's president, Henry Fairfield Osborn, named the animal Velociraptor mongoliensis, the swift seizer from Mongolia. Andrews' adventures, complete with cars crossing the desert and encounters with bandits, made him a celebrity, and he is often suggested as one inspiration for the film character Indiana Jones.

Velociraptor was a turkey-sized, feathered dromaeosaur of Late Cretaceous Mongolia, about two metres long and fifteen kilograms, with winged arms, a stiff tail and a sickle claw that it used to pin prey while its jaws killed, as the fossil of one locked in combat with a Protoceratops shows; there is no evidence it hunted in packs. The film's two-metre scaly raptor was modelled on its larger cousin Deinonychus and made before feathers were found on any dinosaur.